Opening SMI files

Have a problem opening a .SMI file? We collect information about file formats and can explain what SMI files are. Additionally we recommend software suitable for opening or converting such files.

What is the .SMI file type?

Most commonly, the .smi filename extension is a representation of the SMIL Multimedia Presentation (.smi, .smil) file type, with reference to the Synchronized Multimedia Integration Language (SMIL). A W3C recommendation, SMIL is an XML-based markup language and a platform-independent convention for web-based multimedia presentations.

The .smi (more commonly, .smil) file is a short XML-style text file, in which references to multimedia sources (images, sounds), text, transition and playback instructions are given. When processed by a web browser or media player, the .smil (.smi) file causes the presentation to play on the screen. The level of SMIL support varies across browsers and multimedia agents, with SMIL 3.0 content playable by most.

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Any .smil (.smi) file can be directly opened and edited in a text editor, although there are automated tools for creating SMIL presentations. To avoid file-type conflicts, SMIL presentations are recommended to have the .smil extension instead of .smi.

Besides, the .smi extension also relates to the Synchronized Accessible Media Interchange (SAMI) format, denoting the SAMI Closed Caption File (.smi, .sami) file type. SAMI is an HTML-based markup language developed by Microsoft for closed captions (subtitles). A SAMI (.smi) file contains subtitles marked up with HTML tags and cued on a millisecond basis, with CSS used for styling. A single .smi file can provide subtitles in multiple languages. SAMI subtitles (.smi, .sami) are supported by a number of multimedia players and subtitle editors.

Another role of the .smi extension ties it up with the SMILES Molecular Formula (.smi) file type. Standing for Simplified Molecular Input Line Entry Specification, SMILES is a notation system for chemical formulas invented by A. and D. Weininger and further perfected by Daylight Chemical Information Systems, Inc. Here, the .smi file is a text-only (ASCII) SMILES formula of a chemical compound. SMILES formulas follow the well-established graph theory and can be read and visualized in many molecular editors. Thanks to their simplicity, SMILES formulas (.smi) are considered human-readable.

On the Apple Macintosh platform, the .smi extension represents the Self-Mounting Image (.smi) file type and format, a legacy of the classic Apple Mac OS. The .smi file is a disk image wrapped in a Mac OS (PowerPC) executable module that performs the mounting action without the need for Disk Copy. Once commonly used for floppy disks, SMI images were created with the Disk Copy tool. With the Rosetta compatibility layer and Disk Copy, legacy .smi images can be mounted in Mac OS X.

The .smi extension is also known to have been associated with SMS (Short Message Service) archive files (.smi, .smo) on older Siemens (BenQ-Siemens) cellular phones. The .smi file is a binary container for SMS messages archived by the user. Unofficial tools allowed to extract data directly from .smi and .smo archives.